The aging of the American population has significantly changed medical practice over the last century. As is well known, life expectancy first began to increase dramatically in the late 19th century, but at the same time that the numbers of older people have been increasing, the social and cultural meanings of growing old have also changed. It is likely that different cohorts of older people have had different experiences with old age because of the time periods they lived through. This paper offers one way to look at some of the historical changes that have affected the public and the medical profession on the subject of old age by looking at old age through American popular literature in the first half of the 20th century in three overlapping time periods. In the first three decades of the century, the concept of old age was widely defined, and older people (rather than physicians) were the principal authorities in describing the qualities of old age. In the third and fourth decades of the century, the idea of old age was starting to acquire increasing negative connotations, but chronological age itself did not signal the beginning of old age. However, by the late 1930s and 1940s, old age became widely viewed as a specific social and medical problem to be addressed by professionals, and older people had become a recognizable population, with a variety of groups organized around their care. This paper illustrates changes in American understandings of old age within and without the medical profession and suggests ways in which popular conceptions of old age might continue to shift and affect how physicians take care of their older patients in the future.